is known, its treatment remains largely supportive. Removal of the drug should be facilitated by vomiting or gastric lavage. Cardiovascular function should be monitored continuously for at least 48 hours. Arrhythmias should be treated on a case-by-case basis with an appropriate pacemaker and correction of metabolic irregularities, particularly electrolyte imbalances. Respiratory failure should be managed by intubation and artificial respiration. Convulsions should be managed with anticonvulsants (typically diazepam), while monitoring for any worsening in CNS depression. Hypotension can be treated by assuming the corresponding recovery position, by increasing plasma volume with saline infusions, or by pressors, such as adrenaline or dobutamine. Interactions Opipramol can be co-prescribed with other psychiatric drugs, such as antidepressants, anxiolytics and antipsychotics, in which case it can interact with them. Most problematic interactions are generally additive or synergistic, such that, when drugs are combined, their effects intensify, which usually manifests as an increase in side effects, but can also be dangerous, depending on the drugs involved. While opipramol is not a monoamine reuptake inhibitor, any irreversible MAOIs should still be discontinued at least 14 days before treatment. Opipramol can compete with other TCAs, beta blockers, antiarrhythmics (of class 1c) and other drugs for microsomal enzymes, which can lead to slower metabolism and higher plasma concentrations of these drugs. Co-administration of antipsychotics (e.g., haloperidol, risperidone) can increase the plasma concentration of opipramol. Barbiturates and anticonvulsants, on the other hand, can reduce the plasma concentration of opipramol and thereby weaken its therapeutic effect. Pharmacology Pharmacodynamics Opipramol acts as a high affinity sigma receptor agonist, primarily of the σ1 subtype, but also of the σ2 subtype with lower affinity. In one study of σ1 receptor ligands that also included haloperidol, pentazocine, (+)-3-PPP, ditolylguanidine, dextromethorphan, SKF-10,047 ((±)-alazocine), ifenprodil, progesterone, and others, opipramol showed the highest affinity (Ki = 0.2–0.3) for the guinea pig σ1 receptor of all the tested ligands except haloperidol, which it was approximately equipotent with. The sigma receptor agonism of opipramol is thought to be responsible for its therapeutic benefits against anxiety and depression. Unlike other TCAs, opipramol does not inhibit the reuptake of serotonin or norepinephrine. However, it does act as a high affinity antagonist of the histamine H1 receptor and is a low to moderate affinity antagonist of the dopamine D2, serotonin 5-HT2, and α1-adrenergic receptors. H1 receptor antagonism accounts for its antihistamine effects and associated sedative side effects. In contrast to other TCAs, opipramol